path: root/src/lib/nostr.ts

import { Buffer } from "buffer";
import { browser } from "$app/environment";
import {
  decrypted,
  eventToSign,
  password as pw,
  passwordPrompt,
  signer as $signer,
} from "$lib/store";
import { post, wait } from "$lib/utils";
import { bytesToHex, hexToBytes } from "@noble/hashes/utils.js";
import type { EventTemplate } from "nostr-tools";
import { get } from "svelte/store";

let nip04Promise: Promise<typeof import("nostr-tools/nip04")> | undefined;
let nip19Promise: Promise<typeof import("nostr-tools/nip19")> | undefined;
let purePromise: Promise<typeof import("nostr-tools/pure")> | undefined;
let nip44Promise: Promise<typeof import("nostr-tools/nip44")> | undefined;
let relayPromise: Promise<typeof import("nostr-tools/relay")> | undefined;
let nip49Promise: Promise<typeof import("nostr-tools/nip49")> | undefined;

const loadNip04 = () => (nip04Promise ||= import("nostr-tools/nip04"));
const loadNip19 = () => (nip19Promise ||= import("nostr-tools/nip19"));
const loadPure = () => (purePromise ||= import("nostr-tools/pure"));
const loadNip44 = () => (nip44Promise ||= import("nostr-tools/nip44"));
const loadRelay = () => (relayPromise ||= import("nostr-tools/relay"));
const loadNip49 = () => (nip49Promise ||= import("nostr-tools/nip49"));

type User = {
  [key: string]: any;
};

type EncryptParams = {
  message: string;
  recipient: string;
  user: User;
};

export const encrypt = async ({ message, recipient, user }: EncryptParams) => {
  const sk = await getPrivateKey(user);
  const nip04 = await loadNip04();
  return nip04.encrypt(sk, recipient, message);
};

export const decrypt = async ({ event, user }: { event: any; user: any }) => {
  const cache = get(decrypted);
  try {
    let { content, pubkey, id } = event;
    if (cache[id]) return cache[id];
    if (pubkey === user.pubkey) pubkey = event.tags[0][1];

    const nip04 = await loadNip04();
    const message = await nip04.decrypt(await getPrivateKey(user), pubkey, content);

    cache[id] = Buffer.from(message).toString("utf8");
    decrypted.set(cache);

    return cache[id];
  } catch {
    // console.log(e);
  }
};

export const getPrivateKey = async (user: User): Promise<Uint8Array> => {
  let k;
  if (browser) {
    k = localStorage.getItem("nsec");
    if (k) {
      const nip19 = await loadNip19();
      return nip19.decode(k).data as unknown as Uint8Array;
    }
  }

  const { nsec } = user;

  if (nsec) {
    const { decrypt: nip49decrypt } = await loadNip49();
    k = nip49decrypt(nsec, await getPassword());
  } else {
    throw new Error("nsec not available");
  }

  const nip19 = await loadNip19();
  localStorage.setItem("nsec", nip19.nsecEncode(k));
  return k;
};

const decodeNsec = async (nsec: string): Promise<Uint8Array> => {
  const nip19 = await loadNip19();
  const { type, data } = nip19.decode(nsec);
  if (type === "nsec" && data instanceof Uint8Array) return data;
  throw new Error("invalid nsec");
};

export const getNsec = async (user: User) => {
  const nip19 = await loadNip19();
  return nip19.nsecEncode(await getPrivateKey(user));
};

export const setNsec = async (user: User, nsec: string) => {
  const { getPublicKey } = await loadPure();
  user.pubkey = getPublicKey(await decodeNsec(nsec));
  user.nsec = await encryptNsec(nsec);
};

export const encryptNsec = async (nsec: string) => {
  const { encrypt: nip49encrypt } = await loadNip49();
  const d = await decodeNsec(nsec);
  return nip49encrypt(d, await getPassword());
};

export const sign = async (event: any, user?: any) => {
  if (user?.nsec && !get($signer)?.ready) {
    const sk = await getPrivateKey(user);
    const { getPublicKey } = await loadPure();

    $signer.set({
      method: "nsec",
      ready: true,
      params: { sk: bytesToHex(sk), pk: getPublicKey(sk) },
    });
  }

  eventToSign.set(event);
  let unsubscribe: (() => void) | undefined;
  const { method, params } = await new Promise<{ method: string; params: any }>((r, j) => {
    unsubscribe = $signer.subscribe((v) => {
      if (v === "cancel") {
        j("cancelled");
        $signer.set(undefined);
      }
      v?.ready && r(v);
    });
  });
  await unsubscribe?.();
  const signedEvent = await signingMethods[method](event, params);
  eventToSign.set(signedEvent);
  setTimeout(() => eventToSign.set(null), 1000);
  return signedEvent;
};

export const send = (event: EventTemplate) => {
  return post("/event", { event });
};

const getPassword = async (): Promise<string> => {
  if (!get(pw)) passwordPrompt.set(true);
  await wait(() => !!get(pw));
  return get(pw) || "";
};

export const nostrConnectRelay = "wss://relay.nsec.app";

const signingMethods: Record<string, (event: any, params: any) => Promise<any>> = {
  async connect(event: any, { sk, pk, pubkey }: any) {
    const id = crypto.randomUUID();
    const signEvent = {
      id,
      method: "sign_event",
      params: [JSON.stringify(event)],
    };

    const [nip04, { finalizeEvent }] = await Promise.all([loadNip04(), loadPure()]);
    const skBytes = hexToBytes(sk);
    const content = await nip04.encrypt(skBytes, pk, JSON.stringify(signEvent));

    const signedSignEvent = finalizeEvent(
      {
        created_at: Math.round(Date.now() / 1000),
        kind: 24133,
        content,
        tags: [["p", pk]],
      } as EventTemplate,
      skBytes,
    );

    const { Relay } = await loadRelay();
    const relay = await Relay.connect(nostrConnectRelay);
    relay.publish(signedSignEvent);

    return new Promise((resolve) => {
      relay.subscribe([{ kinds: [24133], "#p": [pubkey] }], {
        async onevent(event) {
          pk = event.pubkey;
          try {
            let response;
            try {
              const nip04 = await loadNip04();
              response = JSON.parse(await nip04.decrypt(hexToBytes(sk), pk, event.content));
            } catch {
              const { getConversationKey, decrypt: nip44decrypt } = await loadNip44();
              const ck = await getConversationKey(hexToBytes(sk), pk);
              response = JSON.parse(await nip44decrypt(event.content, ck));
            }

            if (response.id === id) resolve(JSON.parse(response.result));
          } catch (e) {
            console.log("failed to parse nostr connect event", e);
          }
        },
      });
    });
  },

  async nsec(event: any, { sk }: any) {
    const { finalizeEvent } = await loadPure();
    return finalizeEvent(event, hexToBytes(sk));
  },

  async extension(event: any) {
    return window.nostr!.signEvent(event);
  },

  async signer(event: any, { pubkey, sig }: any) {
    event.pubkey = pubkey;
    const { getEventHash } = await loadPure();
    const signedEvent = {
      ...event,
      id: getEventHash(event),
      sig,
    };
    return signedEvent;
  },
};

// Returns all the keys mentioned in the provided event's 'p' tags.
export const pTagKeys = (event: any): string[] => {
  let keys: string[] = [];
  for (const tag of event.tags) {
    if (tag[0] === "p") {
      keys.push(tag[1]);
    }
  }
  return keys;
};